Levered landing gear with inner shock strut

ABSTRACT

A levered landing gear including a first shock strut having and a second shock strut disposed concentrically with the first shock strut. The second shock strut includes a metering pin coupled to a mounting surface of a piston of the second shock strut, and an orifice plate that cooperates with the metering pin to meter an amount of fluid flow as the second shock strut is compressed. The metering pin includes flutes longitudinally arranged on the metering pin between first and second ends of the metering pin, the flutes having a varying depth so that a fluid flow through the flutes is greater at the second end than fluid flow through the flutes at the first end. A truck lever is coupled to both the first shock strut and the second shock strut such that the second shock strut pivots the truck lever relative to the first shock strut.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of UnitedStates Non-Provisional Patent application Ser. No. 15/484,646 filed onApr. 11, 2017 (now U.S. Pat. No. 10,625,849 issued on Apr. 21, 2020) andSer. No. 16/829,359 filed on Mar. 25, 2020 (now U.S. Pat. No. 11,352,129issued on Jun. 7, 2022), the disclosures of which are incorporated byreference herein in their entireties.

BACKGROUND 1. Field

The exemplary embodiments generally relate to aircraft landing gearsystems and aircraft incorporating those landing gear systems and, inparticular, to landing gear assemblies that provide the aircraft withincreased take off height and increased rotation on takeoff and landing.

2. Brief Description of Related Developments

Levered landing gear and conventional shock struts are known and havebeen used on aircraft for many years. Generally, conventional shockstruts include an outer cylinder and an inner cylinder that moverelative to each other. With respect to aircraft, the outer cylinder iscoupled to the airframe and the inner cylinder is coupled to a truck orwheel of the landing gear. The relative movement between the innercylinder and the outer cylinder defines the shock strut stroke.

Aircraft generally include landing gear having the conventional shockstruts to facilitate takeoff, landing, and taxi. For takeoff and landingof the aircraft, a taller landing gear is desired to generate a greaterangle of rotation (e.g. angle of attack) of the aircraft. The landinggear of some aircraft includes a multi-axle truck beam pivotally coupledto a shock strut at, for example, a distal or lower end of the shockstrut to achieve taller takeoff heights; however, multi-axle landinggear increases weight and complexity of the landing gear. The landinggear of other aircraft have single axle landing gear, where additionalground clearance for rotation of the aircraft during takeoff is achievedby increasing the height of landing gear. However, the conventionalshock struts generally have a 1:1 ratio between the vertical axle travelprovided by the shock strut and the shock strut stroke. As such,conventional shock struts are a limiting factor with respect to theamount of vertical axle travel that can be achieved in levered orlevered landing gear.

SUMMARY

The following is a non-exhaustive list of examples, which may or may notbe claimed, of the subject matter according to the present disclosure.

One example of the subject matter according to the present disclosurerelates to a levered landing gear comprising: a first shock strut havinga longitudinal axis; a second shock strut disposed concentrically withthe first shock strut along the longitudinal axis such that the firstshock strut and the second shock strut extend along a common extensionaxis; and a truck lever coupled to both the first shock strut and thesecond shock strut such that the second shock strut pivots the trucklever relative to the first shock strut.

Another example of the subject matter according to the presentdisclosure relates to an aircraft comprising: a vehicle frame; and alevered landing gear coupled to the airframe, the levered landing gearincluding a first shock strut having a longitudinal axis, a second shockstrut disposed concentrically with the first shock strut along thelongitudinal axis such that the first shock strut and the second shockstrut extend along a common extension axis, and a truck lever coupled toboth the first shock strut and the second shock strut such that thesecond shock strut pivots the truck lever relative to the first shockstrut.

Still another example of the subject matter according to the presentdisclosure relates to a method of using a levered landing gear, themethod comprising: extending a first shock strut and a second shockstrut along a common extension axis, wherein the second shock strut isdisposed concentrically with the first shock strut along a longitudinalaxis of the first shock strut; and pivoting a truck lever relative tothe first shock strut as the first shock strut and the second shockstrut extend along the common extension axis, where the truck lever iscoupled to both the first shock strut and the second shock strut.

Yet another example of the subject matter according to the presentdisclosure relates to a levered landing gear comprising: a first shockstrut having a first end and a second end; a truck lever pivotallycoupled to the second end of the first shock strut; and a second shockstrut disposed between the second end of the first shock strut and thetruck lever, where the second shock strut has a first end and a secondend, the first end of the second shock strut being coupled to the secondend of the first shock strut and the second end of the second shockstrut being coupled to the truck lever.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described examples of the present disclosure in generalterms, reference will now be made to the accompanying drawings, whichare not necessarily drawn to scale, and wherein like referencecharacters designate the same or similar parts throughout the severalviews, and wherein:

FIG. 1 is a perspective view of an aircraft incorporating aspects of thepresent disclosure;

FIG. 2A is a side view of a levered landing gear in a compressedconfiguration in accordance with aspects of the present disclosure;

FIG. 2B is a side view of the levered landing gear of FIG. 2A in anextended configuration in accordance with aspects of the presentdisclosure;

FIGS. 3A, 3A-1, and 3A-2 are cross-sectional side views of a portion ofthe levered landing gear of FIGS. 2A and 2B in accordance with aspectsof the present disclosure;

FIG. 3B is a cross-sectional side view of a portion of the leveredlanding gear of FIGS. 2A and 2B in accordance with aspects of thepresent disclosure;

FIG. 3C is a cross-sectional side view of a portion of the leveredlanding gear of FIGS. 2A and 2B in accordance with aspects of thepresent disclosure;

FIGS. 4, 4A, 4B and 4C are cross-sectional side views of a portion ofthe levered landing gear of FIGS. 2A and 2B in accordance with aspectsof the present disclosure;

FIGS. 5A-5C are cross-sectional side views of a portion of the leveredlanding gear of FIGS. 2A and 2B showing a sequence of extension of thelevered landing gear in accordance with aspects of the presentdisclosure;

FIG. 6 is a cross-sectional side view of a levered landing gear in acompressed configuration in accordance with aspects of the presentdisclosure;

FIG. 7A is an exemplary graph illustrating the cooperation between afirst shock strut and a second shock strut of the levered landing gearin accordance with aspects of the present disclosure;

FIG. 7B is an exemplary graph illustrating levered landing gear travelwith respect to ground load in accordance with aspects of the presentdisclosure; and

FIG. 8 is an exemplary flow diagram of a method in accordance withaspects of the present disclosure.

DETAILED DESCRIPTION

The apparatus and methods described herein facilitate a levered landinggear that increases vertical axle travel of the levered landing gearcompared to conventional landing gear having a single shock strut.Accordingly the aspects of the present disclosure described herein canprovide an aircraft including the levered landing gear with an increasedtake-off height and increased aircraft rotation on take-off. Theincreased vertical axle travel of the levered landing gear describedherein can also be used to absorb landing energy. More specifically, thelevered landing gear according to the aspects of the disclosedembodiments include two shock struts disposed relative to each other sothat an amount of travel (e.g. distance of extension and retraction ofeach shock strut) are cumulative so that the two shock struts cooperatewith each other to extend and compress the levered landing gear.

Referring to FIGS. 1, 2A and 2B, the aspects of the present disclosureprovide an aircraft 100 and a levered landing gear 110 having secondshock strut 300 disposed at least partially within a first shock strut200. Placement of the second shock strut 300 within the first shockstrut 200 provides additional travel of the wheel rotation axis AX2 indirection D1 at low load levels (such as, e.g., during takeoff) whilepreserving higher load carrying capabilities of a conventional shockstrut. In one aspect, the second shock strut 300 is at least partiallycontained within the first shock strut 200 so that the additional travelof the wheel rotation axis AX2 in direction D1 is provided withoutincreasing the size or stroke of the first shock strut 200. The leverelement (e.g. the truck lever 220) of the levered landing gear 110 movesthe location of the wheel rotation axis AX2, when for example theaircraft 100 is on the ground, aft (in direction D2) of a longitudinalaxis LAX and axis of extension EX of the first shock strut 200 and thesecond shock strut 300 which may allow a center of gravity CG of theaircraft 100 to move aft in direction D2 as well. Moving the center ofgravity CG of the aircraft 100 aft may increase an amount of cargoand/or fuel carried by the aircraft 100. In addition to the above,disposing the second shock strut 300 within the first shock strut 200provides for the use of the levered landing gear 110 without having tore-design a vehicle frame 100F of the aircraft 100.

Illustrative, non-exhaustive examples, which may or may not be claimed,of the subject matter according to the present disclosure are providedbelow.

Still referring to FIGS. 1, 2A and 2B, the aircraft 100 includes thevehicle frame 100F, the levered landing gear 110, and a landing gear120. The levered landing gear 110 may be the main landing gear, andlanding gear 120 may be a nose landing gear. The levered landing gear110 includes the first shock strut 200 and the second shock strut 300.The first shock strut 200 includes a first end 200E1 and a second end200E2 separated from the first end 200E1 along the longitudinal axisLAX. In one aspect, the second shock strut 300 is disposedconcentrically with the first shock strut 200 along the longitudinalaxis LAX such that the first shock strut 200 and the second shock strut300 extend along an extension axis EX. The extension axis EX is, in oneaspect, a common extension axis along which both the first shock strut200 and the second shock strut 300 extend and retract. For example, thesecond shock strut 300 is disposed concentrically within the first shockstrut 200 along the longitudinal axis LAX. However, in other aspects asdescribed herein with respect to FIG. 6 , the second shock strut 300 maynot be disposed concentrically with the first shock strut and may becoupled to the first shock strut 200 so as to pivot relative to thefirst shock strut 200. The levered landing gear 110 also includes atruck lever 220 that is coupled to both the first shock strut 200 andthe second shock strut 300 such that the second shock strut 300 pivotsthe truck lever 220 relative to the first shock strut 200. The pivotingof the truck lever 220 by the second shock strut 300 increases thetravel of the wheel rotation axis AX2 in direction D1. In one aspect,the truck lever 220 includes but one (i.e., only one) wheel rotationaxis AX2.

Referring also to FIGS. 3A, 3A-1, 3A-2, and 3B, the first shock strut200 includes an outer cylinder 201 and an inner cylinder 202 at leastpartially disposed within the outer cylinder 201, where in one aspect,the second shock strut 300 is disposed at least partially within theinner cylinder 202. The outer cylinder 201 is configured for couplingwith the vehicle frame 100F and the inner cylinder 202 extends andretracts along the extension axis EX relative to the outer cylinder 201.The truck lever 220 includes a first end 220E1 and a second end 220E2,where the first end 220E1 is pivotally coupled to the first shock strut200 at a truck lever pivot axis AX1 and the second end includes thewheel rotation axis AX2. The inner cylinder 202 includes a first end202E1 and a second end 202E2. The first end 202E1 is disposed within theouter cylinder 201 and the second end 202E2 extends from the outercylinder 201 and includes the truck lever pivot axis AX1 so that thetruck lever 220 is pivotally coupled to the inner cylinder 202 of thefirst shock strut 200.

The levered landing gear 110 further includes a connecting link 302 thatcouples the truck lever 220 to the second shock strut 300. Theconnecting link 302 includes a connecting link first end 302E1 and aconnecting link second end 302E2 opposite the connecting link first end302E1. The connecting link first end 302E1 is pivotally coupled to thetruck lever 220 at a connecting pink pivot axis AX3 disposed between thetruck lever pivot axis AX1 and the wheel rotation axis AX2. Theconnecting link second end 302E2 is pivotally coupled to the secondshock strut 300 so that the truck lever 220 is pivotally coupled to boththe first shock strut 200 and the second shock strut 300.

The second shock strut 300 includes a strut cartridge 300C and a piston301 that reciprocates within the strut cartridge 300C. The strutcartridge 300C forms an outer cylinder of the second shock strut 300.Here, because the second shock strut 300 is disposed at least partiallywithin the inner cylinder 202, the piston 301 reciprocates within theinner cylinder 202. The piston 301 has a first end 301E1 that includes aconnecting link mount 301CM and a second end 301E2 that islongitudinally spaced from the first end 301E1. The connecting linkmount 301CM has or otherwise forms a piston pivot axis AX4 where thesecond end 302E2 of the connecting link 302 is pivotally coupled to theconnecting link mount 301CM at the piston pivot axis AX4. The piston 301includes a first bearing 301B1 disposed adjacent the first end 301E1 anda second bearing 301B2 disposed adjacent the second end 301E2, where thefirst bearing 301B1 and the second bearing 301B2 are disposed betweenthe piston 301 and the strut cartridge 300C and engage an interiorsurface 300CI of the strut cartridge 300C so as to guide reciprocatingmovement of the piston 301 within the strut cartridge 300C. As can beseen in FIGS. 3A, 3A-1, and 3A-2 , the connecting link 302 extends fromthe strut cartridge 300C to connect the piston 301 to the truck lever220 such that a first end 300CE1 of the strut cartridge 300C facing thetruck lever 220 is open. In one aspect, the piston 301 further includesa scraper 301SR that interfaces with, e.g., the interior surface 300CIof the strut cartridge 300C, where the scraper 301SR is configured toclean the interior surface 300CI of the strut cartridge 300C as thepiston moves within the strut cartridge 300C. For example, any debriscollected within the strut cartridge 300C may be pushed out of the openfirst end 300CE1 as the second shock strut 300 extends.

The first shock strut 200 of the levered landing gear 110 reacts (e.g.absorbs and/or supports) more of the load VL exerted on the leveredlanding gear 110 than the second shock strut 300. As such, in oneaspect, the levered landing gear 110 comprises a stop member 350 coupledto the inner cylinder 202, where the stop member 350 includes a stopsurface 350S configured to interface with the truck lever 220 such thatreaction forces FR1, FR2 in response to the load VL bypass the secondshock strut 300. For example, the stop member 350 is disposed on thefirst end 220E1 of the inner cylinder 202 adjacent the truck lever pivotaxis AX1 so that as the truck lever 220 pivots about the truck leverpivot axis AX1 in direction D3 a stop surface 220S of the truck lever220 contacts the stop surface 350S of the stop member 350 therebyarresting rotational movement of the truck lever 220 in direction D3 andso that the load VL acting on the truck lever 220 is reacted by theinner cylinder 202 at the stop member 350 and at the truck lever pivotaxis AX1. In one aspect, the stop member 350 may not be provided such aswhere the second shock strut 300 and connecting link 302 are configuredto absorb the reaction forces FR1, FR2. For example, the second shockstrut 300 may be configured to compress to a point where the secondshock strut 300 reaches a solid height (e.g. cannot be compressed anyfurther) so that the load VL is reacted by the inner cylinder 202 of thefirst shock strut 200 at least through the connecting link 302 and thesecond shock strut 300.

The levered landing gear 110 includes at least one torsion link assembly270 that includes at least two torsion links 270A, 270B that couple theouter cylinder 201 of the first shock strut 200 to the inner cylinder202 of the first shock strut 200. The at least one torsion link assembly270 is configured to prevent relative rotation about the commonextension axis EX between the outer cylinder 201 and the inner cylinder202 while allowing relative movement between the outer cylinder 201 andinner cylinder 202 in direction D1 along the common extension axis EX.As described above, the strut cartridge 300C of the second shock strut300 is coupled to the inner cylinder 202 of the first shock strut and assuch the strut cartridge 300C moves in direction D1 as a single unitwith the inner cylinder 202 while being rotationally fixed relative tothe inner cylinder 202. As also described above, the piston 301 of thesecond shock strut 300 is coupled to the truck lever 220 through theconnecting link 302. The truck lever 220 is coupled to the innercylinder 202 and is rotationally fixed with the inner cylinder 202 aboutthe common extension axis EX. As such, because the piston 301 of thesecond shock strut 300 coupled to the truck lever 220 (which is coupledto the inner cylinder 202) and because the strut cartridge 300C of thesecond shock strut 300 is coupled to the inner cylinder 202, the atleast one torsion link assembly 270 is indirectly coupled to the secondshock strut 300 and passively prevents rotation of the second shockstrut 300 relative to the first shock strut 200 through the indirectcoupling. Here, the second shock strut 300 is passively prevented fromrotating by the at least one torsion link assembly 270 because the atleast one torsion link assembly 270 prevents rotation of the truck lever220 relative to the outer cylinder 201 and the at least one torsion linkassembly is not directly coupled to the second shock strut 300.

Referring to FIGS. 3A, 3A-1, 3A-2 and 3B, the inner cylinder 202includes an inner chamber 202C, that is bifurcated into a first shockstrut compression chamber 380 and a second shock strut compressionchamber 390. Fluid UF1, such as a compressed gas, within the first shockstrut compression chamber 380 acts as a spring to extend the innercylinder 202 relative to the outer cylinder 201 as the aircraft 100takes off. Fluid LF1, such as compressed gas, within the second shockstrut fluid compression chamber 390 acts as a spring to extend thesecond shock strut 300 relative to the inner cylinder 202 as theaircraft 100 takes off. The fluid UF1 in the first shock strut 200 has afirst pressure and the fluid LF1 in the second shock strut 300 has asecond pressure, where in one aspect, the first pressure is differentthan the second pressure so as to tailor performance of the leveredlanding gear 110 to, for example, a particular aircraft 100 (or loadingof the aircraft) on which the levered landing gear 110 is installed. Inone aspect, strut cartridge 300C of the second shock strut 300 isinserted into the inner cylinder 202 such that the strut cartridge 300Cbifurcates the inner chamber 202C and defines the second shock strutfluid compression chamber 390. The strut cartridge 300C of the secondshock strut 300 is coupled to the inner cylinder 202 of the first shockstrut 200 in any suitable manner, such as by one or more removablefasteners so that the second shock strut 300 is removable from the firstshock strut 200, such as for maintenance of the levered landing gear110. The strut cartridge 300C includes an elongated tube 300T having thefirst end 300CE1 and the second end 300CE2 and an end cap 300EC disposedat the second end 300CE2. In one aspect the end cap 300EC defines astrut bulkhead 200BH of the first shock strut 200 where the bulkhead200BH separates the first shock strut 200 and the second shock strut 300so that fluids UF1 (such as compressed gas) and LF2 (such as hydraulicoil) of the first shock strut 200 do not mix with fluids LF1 (such ascompressed gas) and LF2 (such as hydraulic oil) of the second shockstrut 300 and so that the first shock strut 200 and the second shockstrut 300 are maintained at different operating pressures.

The first shock strut 200 is a gas/oil strut (e.g. also known as an OLEOstrut) in which the gas, such as fluid UF1 is disposed above hydraulicoil, such as fluid UF2 where the gas acts as a spring and causesextension of the first shock strut 200 as well as absorb compressionforces of the first shock strut 200 while the oil dampens theextension/retraction of the first shock strut 200. Retraction orcompression of the first shock strut 200 causes the hydraulic oil (suchas fluid UF2) to be forced through fluid flow passages (such as aperture310PA in an orifice plate 310P of the first shock strut 200) at acontrolled rate which provides energy absorption (e.g. damping) andcontrols a rate at which the first shock strut 200 reacts to appliedloads, such as load VL. The first shock strut includes features (such asthe metering pin 303) to change a size of the fluid flow passages (suchas aperture 310PA) relative to a stroke of the first shock strut 200(e.g. the difference between extension length LE2 and LE2′). As will bedescribed below the metering pin 303 has a variable area along itslength and is positioned within the aperture 310PA, where the aperture310PA has a fixed area (i.e. the area of the aperture 310PA does notchange). Changing the size of the fluid flow passages includes changinga diameter of the metering pin 330 along its length (e.g. the meteringpin has a conical shape), or by providing flutes 330F that vary in oneor more of a depth (e.g. varying depth 330FD) of the flute 330F or awidth 330FW of the flute 330F along the length of the metering pin 303.

The strut bulkhead 200BH of the first shock strut 200 includes themetering pin 330 of the first shock strut 200 so that the first shockstrut 200 includes variably sized fluid passages 310FP configured tocontrol a load VL applied to the outer cylinder 201 of the first shockstrut 200, where the outer cylinder 201 forms a piston of the firstshock strut 200. In one aspect, the strut bulkhead 200BH and themetering pin 330 may be formed as a single monolithic member while inother aspects the metering pin 330 may be coupled to the strut bulkhead200BH in any suitable manner, such as by any chemical or mechanicalfastener. An orifice support tube 310 is coupled to the outer cylinder201 of the first shock strut 200 so as to extend within the innercylinder 202 towards the strut bulkhead 200BH. The orifice support tube310 includes an orifice plate 310P that includes an aperture 310PAthrough which the metering pin 330 extends. The metering pin 330 of thefirst shock strut 200 includes a first end 330E1 proximate the strutbulkhead 200BH and a second end 330E2 longitudinally separated from thefirst end 330E1 where the metering pin 330 has a constant outer diameterOD1 between the first end 330E1 and the second end 330E2, where theouter diameter OD1 is sized to slidingly interface with the aperture310PA of the orifice plate 310P.

In other aspects, the metering pin 330 may have a tapered outer diameterin lieu of flutes 330F as described herein where the tapered outerdiameter controls fluid flow through the aperture 310PA in a mannersubstantially similar to that described herein with respect to theflutes 330F. The metering pin 330 includes the flutes 330F which arelongitudinally arranged on the metering pin 330 between the first end330E1 and the second end 330E2 where the flutes 330F having a varyingdepth 330FD relative to the outer diameter OD1 so as to form thevariably sized fluid passages 310FP and so that a fluid flow through theflutes 330F at the interface between the metering pin 330 and theaperture 310PA is greater at the second end 330E2 than fluid flowthrough the flutes at the first end 330E1. Here, the fluid UF2 passesthrough the variably sized fluid passages 310FP to control the reactiveload on the outer cylinder 202 (e.g. piston) of the first shock strut200 where the load on the outer cylinder 202 is decreased when thesecond end 330E2 (where the flute depth is the deepest) of the meteringpin 330 is adjacent the orifice plate 310P and is increased when thefirst end 330E1 of the metering pin 330 is adjacent the orifice plate310P (where the flute depth is the shallowest).

The first shock strut 200 also includes features that control a rate ofextension of the first shock strut 200. For example, the first shockstrut 200 includes a recoil valve 310RV that is configured such thatextension of the first shock strut 200 causes the fluid UF2 to be forcedthrough orifices in the recoil valve 310RV at a controlled rate that inturn controls the rate at which the first shock strut 200 extends. Inone aspect the recoil valve 320RV is coupled to the inner cylinder 202in any suitable manner. Upon compression of the first shock strut 200the recoil valve 310RV is configured such that the orifices are openallowing the fluid UF2 to flow freely through fluid passages 310FP.

Referring to FIGS. 3A, 3A-1, 3A-2, 3B, 3C, 4 and 4A-4C, the second shockstrut 300 is a gas/oil strut (e.g. also known as an OLEO strut) in whichthe gas, such as fluid LF1 is disposed above hydraulic oil, such asfluid LF2 where the gas acts as a spring and causes extension of thesecond shock strut 300 as well as absorb compression forces of thesecond shock strut 300 while the oil dampens the extension/retraction ofthe second shock strut 300. Retraction or compression of the secondshock strut 300 causes the hydraulic oil (such as fluid LF2) to beforced through fluid flow passages (such as aperture 320PA in an orificeplate 320P of the second shock strut 300) at a controlled rate whichprovides energy absorption (e.g. damping) and controls a rate at whichthe second shock strut 300 reacts to applied loads, such as load VL. Thesecond shock strut includes features (such as the metering pin 340) tochange a size of the fluid flow passages (such as aperture 320PA)relative to a stroke of the second shock strut 300 (e.g. extensionlength LE3). As described herein the metering pin 340 has a variablearea along its length and is positioned within the aperture 320PA, wherethe aperture 320PA has a fixed area (i.e. the area of the aperture 320PAdoes not change). In one aspect, changing the size of the fluid flowpassages includes changing a diameter of the metering pin 340 along itslength, or by providing flutes 340F that vary in one or more of a depth(e.g. varying depth 340FD) of the flute 340F or a width 340FW of theflute 340F along the length of the metering pin 340.

The piston 301 of the second shock strut 300 includes the metering pin340 of the second shock strut 300 so that the second shock strut 300includes variably sized fluid passages 320FP configured to control aload VL applied to the piston 301 of the second shock strut 300. Themetering pin 340 is coupled to a mounting surface 301MS of the piston301 of the second shock strut 300. In one aspect, piston 301 and themetering pin 340 may be formed as a single monolithic member while inother aspects the metering pin 340 may be coupled to the piston in anysuitable manner, such as by any chemical or mechanical fastener. Anorifice support tube 320 is coupled to the first shock strut 200, suchas coupled to the strut bulkhead 200BH, so as to extend within the strutcartridge 300C towards the piston 301. The orifice support tube 320includes an orifice plate 320P that includes an aperture 320PA throughwhich the metering pin 340 extends. The metering pin 340 of the secondshock strut 300 includes a first end 340E1 proximate the first end 301E1of the piston 301 and a second end 340E2 longitudinally separated fromthe first end 340E1 where the metering pin 340 has a constant outerdiameter OD2 between the first end 340E1 and the second end 340E2, wherethe outer diameter OD2 is sized to slidingly interface with the aperture320PA of the orifice plate 320P.

In other aspects, the metering pin 340 may have a tapered outer diameterin lieu of the flutes as described herein where the tapered outerdiameter controls fluid flow through the aperture 320PA in a mannersubstantially similar to that described herein with respect to theflutes 340F. The metering pin 340 includes the flutes 340F which arelongitudinally arranged on the metering pin 340 between the first end340E1 and the second end 340E2 where the flutes 340F having a varyingdepth 340FD relative to the outer diameter OD2 so as to form thevariably sized fluid passages 320FP and so that a fluid flow through theflutes 340F at the interface between the metering pin 340 and theaperture 320PA is greater at the second end 340E2 than fluid flowthrough the flutes 340F at the first end 340E1. Here the fluid LF2passes through the variably sized fluid passages 320FP to control thereactive load on the piston 301 of the second shock strut 300 where theload on the piston 301 is decreased when the second end 340E2 (where theflute depth is the deepest) of the metering pin 340 is adjacent theorifice plate 320P and is increased when the first end 340E1 of themetering pin 340 is adjacent the orifice plate 320P (where the flutedepth is the shallowest).

The second shock strut 300 also includes features that control a rate ofextension of the second shock strut 300. For example, the second shockstrut 300 includes a recoil valve 320RV (which is substantially similarto recoil valve 310RV) that is configured such that extension of thesecond shock strut 300 causes the fluid LF2 to be forced throughorifices 320RVO in the recoil valve 320RV at a controlled rate that inturn controls the rate at which the second shock strut 300 extends. Inone aspect, the recoil valve 320RV is coupled to the orifice supporttube 320 while in other aspects the recoil valve 320RV is coupled to thestrut cartridge 300C in any suitable manner. Upon compression of thesecond shock strut 300 the recoil valve 320RV is configured such thatthe orifices 320RVO are open allowing the free flow of fluid LF2 throughthe variably sized fluid passages 320FP. The compression and extensionof the second shock strut 300 may be set or otherwise adjusted tocompliment the compression and extension of the first shock strut 200such that the second shock strut 300 does not cause any undesiredrebound during extension and retraction of the levered landing gear 110.

In one aspect, referring to FIGS. 3B, 3C, 4 and 4A-4C the second shockstrut 300 is serviceable through the first shock strut 200 so that, forexample, the second shock strut 300 is filled with gas and oil throughthe first shock strut 200 so that the second shock strut 300 is at apredetermined operating pressure and oil level. A second shock strutservice fitting 400 is disposed on the first shock strut 200 and atleast one fluid flow aperture 410 extends through a wall 300W of thestrut cartridge 300C of the second shock strut 300. For example, thesecond shock strut service fitting 400 is disposed on the inner cylinder202 of the first shock strut 200 adjacent the first end 220E1 of theinner cylinder 202. The strut cartridge 300C of the second shock strutis coupled to the inner cylinder 202 of the first shock strut 200 and isconfigured so that a space exists between an outer surface 30000 of thestrut cartridge 300C and an interior surface 202IS of the inner cylinder202 of the first shock strut 200, where the space defines a fluidpassage 420 between the second shock strut service fitting 400 and theat least one fluid flow aperture 410 of the strut cartridge 300C. Thesecond shock strut service fitting 400 is coupled to the inner cylinder202 so as to be in communication with the fluid passage 420 so that asgas and/or oil flows into the levered landing gear 110 the fluid entersand passes through the fluid flow passage 420 and through the at leastone fluid flow aperture 410 thereby entering the second shock strutfluid compression chamber 390 within the strut cartridge 300C. Thesecond shock strut service fitting 400 may include any suitable checkvalve so that once the gas/oil enters into the fluid flow passage 420the fluid cannot exit through the second shock strut service fitting400.

Referring to FIG. 6 , as noted above, the second shock strut 300 may bepivotally coupled to the inner cylinder 202 of the first shock 200 andthe truck lever 220. For example, the second shock strut 300 is disposedbetween the second end 202E2 of the first shock strut 200 inner cylinder202 and the truck lever 220, where the second shock strut 300 has afirst end 300CE1′ and a second end 300CE2′, the first end 300CE1′ of thesecond shock strut 300 is coupled to the second end 202E2 of the firstshock strut 200 inner cylinder 202 and the second end 300CE2′ of thesecond shock strut 300 is coupled to the truck lever 220. For example,in this aspect, the second shock strut 300 includes an outer cylinder300C′ forming one of the first end 300CE1′ and second end 300CE2′ of thesecond shock strut 300 and an inner cylinder 301′ forming the other ofthe first end 300CE1′ and second end 300CE2′ of the second shock strut300 where the second shock strut 300 is pivotally coupled to the innercylinder 202 of the first shock strut 200 and is directly (e.g. withoutany intervening coupling members) pivotally coupled to the truck lever220. The outer cylinder 300C′ and the inner cylinder 301′ move relativeto each other in a manner similar that with the strut cartridge 300C andpiston 301.

In one aspect, the outer cylinder 300C′ is substantially similar to thestrut cartridge 300C in that the outer cylinder 300C′ includes at leastthe second shock strut fluid compression chamber 390, the orificesupport tube 320, recoil valve 320RV and the orifice plate 320P of thestrut cartridge 300C described above. In one aspect, the inner cylinder301′ is substantially similar to the piston 301 in that the innercylinder 301′ includes the metering pin 340 (similar to inner cylinder202 of the first shock strut 200). The outer cylinder 300C′ is pivotallycoupled to the inner cylinder 202 of the first shock strut 200 at pivotaxis AX4′ so as to be located in a fixed spatial position relative tothe inner cylinder 202 (e.g. the pivot axis AX4′ does not move relativeto the inner cylinder 202). The pivot axis AX4′ may be formed by a mount600CM that is integrally formed as a monolithic member with the innercylinder 202 while in other aspects, the pivot axis AX4′ may be formedby the mount 600CM that is formed by any suitable cartridge 600 that isinserted into the inner cylinder 202 in a manner substantially similarto that described above with respect to the strut cartridge 300C. Theinner cylinder 301′ is pivotally coupled to the truck lever 220 at theconnecting link pivot axis AX3 so that extension of the second shockstrut 300 between the axes AX4′ and AX3 causes the truck lever to pivotabout the truck lever pivot axis AX1 in direction D4, so that incombination with the extension of the first shock strut 200, the leveredlanding gear is extended from extension length LE1 to extension lengthLE1′ as illustrated in FIGS. 2A and 2B; and similarly is compressed fromextension length LE1′ to extension length LE1 where the truck leverrotates in direction D3 about the truck lever pivot axis AX1.

Referring now to FIGS. 2A and 2B, the first shock strut 200 and thesecond shock strut 300 are configured so as to cooperate with each otherto absorb landing energy as well as to cooperate with each other toextend the levered landing gear. An extension length (e.g. thedifference between extension lengths LE1′ and LE1) of the leveredlanding gear 110 is defined by a combination of an extension length(e.g. the difference between extension lengths LE2′ and LE2) of thefirst shock strut 200 and an extension length LE3 of the second shockstrut 300. For example, the levered landing gear 110 has a retracted orcompressed extension length LE1 and an extended extension length LE1′.To extend from extension length LE1 to extension length LE1′, the firstshock strut 200 extends from extension length LE2, which is a compressedor retracted configuration of the first shock strut, to extension lengthLE2′. While the first shock strut 200 is extending, at least part waythrough the extension of the first shock strut 200, the second shockstrut 300 extends a distance LE3 providing the levered landing gear 110with an overall extension length of LE1′. Referring also to FIGS. 3B, 3Cand 5A-5C, when the second shock strut 300 is in the retractedconfiguration, the truck lever 220 is in contact with the stop member350 (or in other aspects the second shock strut is at a solid height).As the aircraft 100 is taking off, the first shock strut extends indirection D1A where the extension of the first shock strut 200 and thesecond shock strut 300 occurs substantially simultaneously over at leasta portion of the extension of the levered landing gear 110, noting theposition of the strut bulkhead 200BH relative to the outer cylinder 201in FIGS. 5A and 5B. As the load VL on the levered landing gear 110decreases due to lift generated by wings of the aircraft 100 the secondshock strut 300 extends from the retracted configuration where the fluidLF1 expands to push the piston 301 in direction D1A so that theconnecting link 302 pushes on the truck lever 220 to rotate the trucklever 220 about the truck lever pivot axis AX4 in direction D4.

Retraction of the levered landing gear 110 from the extension lengthLE1′ to the extension length LE1 occurs in substantially reverse mannerto that described above. For example, upon landing of the aircraft 100the load VL acts on the truck lever 220 to rotate the truck lever 220 indirection D3 about the truck lever pivot axis AX1. Rotation of the trucklever 220 in direction D3 causes the connecting link 302 to push on thepiston 301, thereby compressing the fluid LF1 so that at least a portionof the load VL is absorbed by the fluid FL1. As the load VL increases,e.g., from decreased lift generated by the wings of the aircraft 100 orby downward motion of the aircraft 100, the inner cylinder 202 of thefirst shock strut 200 moves in direction D1B relative to the outercylinder 201 to compress the fluid UL1 so that at least a portion of theload VL is absorbed by the fluid UL1. As described above, the retractionof the first shock strut 200 and the second shock strut 300 occurssubstantially simultaneously over at least a portion of the extension ofthe levered landing gear 110, again noting the position of the strutbulkhead 200BH relative to the outer cylinder 201 in FIGS. 5A and 5B. Asthe load VL continues to increase the truck lever 220 rotates indirection D3 so that the truck lever 220 contacts the stop member 350thereby transferring the entirety of the load VL to the first shockstrut 200.

Cooperation between the first shock strut 200 and the second shock strut300 during extension and retraction of the levered landing gear isillustrated in the graph shown in FIG. 7A. In this graph the load on thefirst shock strut 700 and the load on the second shock strut 701 isshown relative to travel (e.g. extension and retraction) of the leveredlanding gear 110. The graph of FIG. 7A illustrates the first shock strut200 and the second shock strut 300 working together to extend andretract the landing and absorb the load VL where, for example, thelanding energy absorption is managed between the first shock strut 200and the second shock strut 300 by regulating the flow of fluid FL2 (suchas the hydraulic oil) in the second shock strut 300 so that the trucklever 220 contacts the stop member 350 of the inner cylinder 202 of thefirst shock strut at a predetermined velocity.

Referring also to FIG. 7B, a graph is illustrated showing the take-offperformance 710 of the levered landing gear 110 compared to the take offperformance 715 of a conventional landing gear CSS having a single shockstrut (with an outer cylinder CSSO and an inner cylinder CSSI that aremoveable relative to each other) and a single wheel axis CWA. Here itcan be seen that, at full extension, the increased extension LE3 of thelevered landing gear 110 provided by the second shock strut 300(compared to the conventional landing gear CSS) provides the aircraftwith an increased ground load, which may result in increased rotationangle ROT performance of the aircraft at lake off (and landing). Forexample, the aspects of the present disclosure may provide the aircraftwith an additional 1 degree or more of rotation on take-off (andlanding) compared to an aircraft that has the conventional single shockstrut/single wheel axis landing gear. FIG. 7A also illustrates thesubstantially simultaneous extension of both the first shock strut 200and the second shock strut 300 (as described above with respect to FIGS.5A-5C) over at least a portion of the extension of the levered landinggear 110.

Referring now to FIGS. 3A, 3A-1, 3A-2, 6 and 8 an exemplary operation ofthe levered landing gear 110 will be described. In one aspect, thesecond shock strut is disposed at least partially within the first shockstrut (FIG. 8 , Block 800). In one aspect, the second shock strut 300 isdisposed concentrically with and/or within a first shock strut 200,along the longitudinal axis LAX of the first shock strut 200, such thatthe first shock strut 200 and the second shock strut 300 extend along acommon extension axis EX; while in other aspects, the second shock strut300 is pivotally coupled to the first shock strut 200 where the firstshock strut extends along extension axis EX and the second shock strut300 extends along extension axis EX′ where the spatial orientation ofthe extension axis EX′ of the second shock strut 300 changes relative tothe extension axis EX of the first shock strut 200 as the leveredlanding gear 110 extends and retracts in direction D1. Fluid is added tothe second shock strut (FIG. 8 , Block 810). For example, fluid may beadded to the second shock strut 300 through the second shock strutservice fitting 400 as described above; while in other aspects, such asshown in FIG. 6 , the fluid may be added to the second shock strut 300through a second shock strut service fitting 400′ directly coupled tothe inner cylinder 301′. The truck lever 220 is coupled to both thefirst shock strut 200 and the second shock strut 300 (FIG. 8 , Block820) in the manners described above so that the first shock strut 200and the second shock strut 300 cooperatively extend the levered landinggear 110 and cooperatively absorb landing energy (FIG. 8 , Block 830).

The following are provided in accordance with the aspects of the presentdisclosure:

-   -   A1. A levered landing gear comprising:    -   a first shock strut having a longitudinal axis;    -   a second shock strut disposed concentrically with and/or within        the first shock strut along the longitudinal axis such that the        first shock strut and the second shock strut extend along a        common extension axis; and    -   a truck lever coupled to both the first shock strut and the        second shock strut such that the second shock strut pivots the        truck lever relative to the first shock strut.    -   A2. The levered landing gear of paragraph A1, wherein    -   the first shock strut includes an outer cylinder and an inner        cylinder at least partially disposed within the outer cylinder,        the outer cylinder being configured for coupling with a vehicle        frame and the inner cylinder extends and retracts relative to        the outer cylinder.    -   A3. The levered landing gear of paragraph A2, wherein the second        shock strut is disposed at least partially within the inner        cylinder.    -   A4. The levered landing gear of paragraph A2, wherein the second        shock strut includes a piston that reciprocates within the inner        cylinder.    -   A5. The levered landing gear of paragraph A4, further comprising        a connecting link coupling the piston to the truck lever.    -   A6. The levered landing gear of paragraph A2, wherein the inner        cylinder includes an inner chamber, the inner chamber being        bifurcated into a first shock strut fluid compression chamber        and a second shock strut fluid compression chamber, where fluid        within the first shock strut compression chamber extends the        inner cylinder relative to the outer cylinder and fluid within        the second shock strut fluid compression chamber extends the        second shock strut relative to the inner cylinder.    -   A7. The levered landing gear of paragraph A6, wherein the second        shock strut comprises a strut cartridge inserted into the inner        chamber, where the strut cartridge bifurcates the inner chamber        and defines the second shock strut fluid compression chamber.    -   A8. The levered landing gear of paragraph A7, wherein the strut        cartridge comprises an elongated tube and an end cap, the end        cap defines a strut bulkhead of the first shock strut.    -   A9. The levered landing gear of paragraph A8, wherein the strut        bulkhead of the first shock strut includes a metering pin of the        first shock strut.    -   A10. The levered landing gear of paragraph A9, wherein the        metering pin of the first shock strut includes a first end        proximate the strut bulkhead, a second end longitudinally        separated from the first end, and flutes longitudinally arranged        on the metering pin between the first end and the second end,        the flutes having a varying depth so that a fluid flow through        the flutes is greater at the second end than fluid flow through        the flutes at the first end.    -   A11. The levered landing gear of paragraph A2, further        comprising a stop member coupled to the inner cylinder, the stop        member including a stop surface configured to interface with the        truck lever such that reaction forces bypass the second shock        strut.    -   A12. The levered landing gear of paragraph A1, wherein    -   the truck lever includes a first end and a second end, the first        end being pivotally coupled to the first shock strut at a truck        lever pivot axis and the second end includes a wheel rotation        axis; and    -   a connecting link having a connecting link first end and a        connecting link second end opposite the connecting link first        end, the connecting link first end being coupled to the truck        lever between the truck lever pivot axis and the wheel rotation        axis, and the connecting link second end being coupled to the        second shock strut.    -   A13. The levered landing gear of paragraph A12, wherein the        connecting link is pivotally coupled to both the second shock        strut and the truck lever.    -   A14. The levered landing gear of paragraph A12, wherein the        truck lever includes but one wheel rotation axis.    -   A15. The levered landing gear of paragraph A1, wherein an        extension length of the levered landing gear is defined by a        combination of an extension length of the first shock strut and        an extension length of the second shock strut.    -   A16. The levered landing gear of paragraph A1, further        comprising at least one torsion link assembly coupling an inner        cylinder and outer cylinder of the first shock strut.    -   A17. The levered landing gear of paragraph A16, wherein the at        least one torsion link assembly is configured to prevent        rotation of the second shock strut relative to the first shock        strut.    -   A18. The levered landing gear of paragraph A1, wherein the first        shock strut and the second shock strut are configured so as to        cooperate with each other to absorb landing energy.    -   A19. The levered landing gear of paragraph A1, wherein the first        shock strut and the second shock strut are configured so as to        cooperate with each other to extend the levered landing gear.    -   A20. The levered landing gear of paragraph A1, wherein the        second shock strut comprises:    -   a metering pin coupled to a mounting surface of a piston of the        second shock strut; and    -   an orifice plate that cooperates with the metering pin to meter        an amount of fluid flow as the second shock strut is compressed.    -   A21. The levered landing gear of paragraph A20, wherein the        metering pin includes a first end proximate the mounting surface        of the piston, a second end longitudinally separated from the        first end, and flutes longitudinally arranged on the metering        pin between the first end and the second end, the flutes having        a varying depth so that a fluid flow through the flutes is        greater at the second end than fluid flow through the flutes at        the first end.    -   A22. The levered landing gear of paragraph A1, wherein the        second shock strut includes a strut cartridge and a piston that        reciprocates within the strut cartridge, the piston having a        first end including a connecting link mount and a second end,        longitudinally spaced from the first end.    -   A23. The levered landing gear of paragraph A22, wherein the        piston further comprises a first bearing disposed adjacent the        first end and a second bearing disposed adjacent the second end,        the first bearing and the second bearing being disposed between        the piston and the strut cartridge.    -   A24. The levered landing gear of paragraph A22, wherein the        piston further comprises a scraper that interfaces with the        strut cartridge, the scraper being configured to clean an        interior surface of the strut cartridge as the piston moves        within the strut cartridge.    -   A25. The levered landing gear of paragraph A1, wherein the first        shock strut includes variably sized fluid passages configured to        control a load applied to an outer cylinder of the first shock        strut, where the outer cylinder forms a piston of the first        shock strut.    -   A26. The levered landing gear of paragraph A1, wherein the        second shock strut includes variably sized fluid passages        configured to control a load applied to a piston of the second        shock strut.    -   A27. The levered landing gear of paragraph A1, further        comprising a second shock strut service fitting disposed on the        first shock strut, and at least one fluid flow aperture        extending through a wall of a strut cartridge of the second        shock strut, wherein a space between an outer surface of the        second shock strut and an interior surface of the first shock        strut defines a fluid passage between the second shock strut        service fitting and the at least one fluid flow aperture.    -   A28. An aircraft comprising the levered landing gear of any one        of paragraphs A1 to A27.    -   B1. An aircraft comprising:    -   a vehicle frame; and    -   a levered landing gear coupled to the airframe, the levered        landing gear including    -   a first shock strut having a longitudinal axis,    -   a second shock strut disposed concentrically with and/or within        the first shock strut along the longitudinal axis such that the        first shock strut and the second shock strut extend along a        common extension axis, and    -   a truck lever coupled to both the first shock strut and the        second shock strut such that the second shock strut pivots the        truck lever relative to the first shock strut.    -   B2. The aircraft of paragraph B1, wherein    -   the first shock strut includes an outer cylinder and an inner        cylinder at least partially disposed within the outer cylinder,        the outer cylinder being configured for coupling with the        vehicle frame and the inner cylinder extends and retracts        relative to the outer cylinder.    -   B3. The aircraft of paragraph B2, wherein the second shock strut        is disposed at least partially within the inner cylinder.    -   B4. The aircraft of paragraph B2, wherein the second shock strut        includes a piston that reciprocates within the inner cylinder.    -   B5. The aircraft of paragraph B4, further comprising a        connecting link coupling the piston to the truck lever.    -   B6. The aircraft of paragraph B2, wherein the inner cylinder        includes an inner chamber, the inner chamber being bifurcated        into a first shock strut fluid compression chamber and a second        shock strut fluid compression chamber, where fluid within the        first shock strut compression chamber extends the inner cylinder        relative to the outer cylinder and fluid within the second shock        strut fluid compression chamber extends the second shock strut        relative to the inner cylinder.    -   B7. The aircraft of paragraph B6, wherein the second shock strut        comprises a strut cartridge inserted into the inner chamber,        where the strut cartridge bifurcates the inner chamber and        defines the second shock strut fluid compression chamber.    -   B8. The aircraft of paragraph B7, wherein the strut cartridge        comprises an elongated tube and an end cap, the end cap defines        a strut bulkhead of the first shock strut.    -   B9. The aircraft of paragraph B8, wherein the strut bulkhead of        the first shock strut includes a metering pin of the first shock        strut.    -   B10. The aircraft of paragraph B9, wherein the metering pin of        the first shock strut includes a first end proximate the strut        bulkhead, a second end longitudinally separated from the first        end, and flutes longitudinally arranged on the metering pin        between the first end and the second end, the flutes having a        varying depth so that a fluid flow through the flutes is greater        at the second end than fluid flow through the flutes at the        first end.    -   B11. The aircraft of paragraph B2, further comprising a stop        member coupled to the inner cylinder, the stop member including        a stop surface configured to interface with the truck lever such        that reaction forces bypass the second shock strut.    -   B12. The aircraft of paragraph B1, wherein    -   the truck lever includes a first end and a second end, the first        end being pivotally coupled to the first shock strut at a truck        lever pivot axis and the second end includes a wheel rotation        axis; and    -   a connecting link having a connecting link first end and a        connecting link second end opposite the connecting link first        end, the connecting link first end being coupled to the truck        lever between the truck lever pivot axis and the wheel rotation        axis, and the connecting link second end being coupled to the        second shock strut.    -   B13. The aircraft of paragraph B12, wherein the connecting link        is pivotally coupled to both the second shock strut and the        truck lever.    -   B14. The aircraft of paragraph B12, wherein the truck lever        includes but one wheel rotation axis.    -   B15. The aircraft of paragraph B1, wherein an extension length        of the levered landing gear is defined by a combination of an        extension length of the first shock strut and an extension        length of the second shock strut.    -   B16. The aircraft of paragraph B1, further comprising at least        one torsion link assembly coupling an inner cylinder and outer        cylinder of the first shock strut.    -   B17. The aircraft of paragraph B16, wherein the at least one        torsion link assembly is configured to prevent rotation of the        second shock strut relative to the first shock strut.    -   B18. The aircraft of paragraph B1, wherein the first shock strut        and the second shock strut are configured so as to cooperate        with each other to absorb landing energy.    -   B19. The aircraft of paragraph B1, wherein the first shock strut        and the second shock strut are configured so as to cooperate        with each other to extend the levered landing gear.    -   B20. The aircraft of paragraph B1, wherein the second shock        strut comprises:    -   a metering pin coupled to a mounting surface of a piston of the        second shock strut; and    -   an orifice plate that cooperates with the metering pin to meter        an amount of fluid flow as the second shock strut is compressed.    -   B21. The aircraft of paragraph B20, wherein the metering pin        includes a first end proximate the mounting surface of the        piston, a second end longitudinally separated from the first        end, and flutes longitudinally arranged on the metering pin        between the first end and the second end, the flutes having a        varying depth so that a fluid flow through the flutes is greater        at the second end than fluid flow through the flutes at the        first end.    -   B22. The aircraft of paragraph B1, wherein the second shock        strut includes a strut cartridge and a piston that reciprocates        within the strut cartridge, the piston having a first end        including a connecting link mount and a second end,        longitudinally spaced from the first end.    -   B23. The aircraft of paragraph B22, wherein the piston further        comprises a first bearing disposed adjacent the first end and a        second bearing disposed adjacent the second end, the first        bearing and the second bearing being disposed between the piston        and the strut cartridge.    -   B24. The aircraft of paragraph B22, wherein the piston further        comprises a scraper that interfaces with the strut cartridge,        the scraper being configured to clean an interior surface of the        strut cartridge as the piston moves within the strut cartridge.    -   B25. The aircraft of paragraph B1, wherein the first shock strut        includes variably sized fluid passages configured to control a        load applied to an outer cylinder of the first shock strut,        where the inner cylinder forms a piston of the first shock        strut.    -   B26. The aircraft of paragraph B1, wherein the second shock        strut includes variably sized fluid passages configured to        control a load applied to a piston of the second shock strut.    -   B27. The levered landing gear of paragraph B1, further        comprising a second shock strut service fitting disposed on the        first shock strut, and at least one fluid flow aperture        extending through a wall of a strut cartridge of the second        shock strut, wherein a space between an outer surface of the        second shock strut and an interior surface of the first shock        strut defines a fluid passage between the second shock strut        service fitting and the at least one fluid flow aperture.    -   C1. A method of making a levered landing gear, the method        comprising:    -   disposing a second shock strut concentrically with and/or within        a first shock strut, along a longitudinal axis of the first        shock strut, such that the first shock strut and the second        shock strut extend along a common extension axis; and    -   coupling a truck lever to both the first shock strut and the        second shock strut, such that the second shock strut pivots the        truck lever relative to the first shock strut as the first shock        strut and the second shock strut extend along the common        extension axis.    -   C2. The method of paragraph C1, wherein disposing second shock        strut concentrically with and/or within a first shock strut        includes positioning the first shock strut and the second shock        strut relative to each other so that the first shock strut and        the second shock strut cooperatively absorb landing energy.    -   C3. The method of paragraph C1, wherein disposing second shock        strut concentrically with and/or within a first shock strut        includes positioning the first shock strut and the second shock        strut relative to each other so that the first shock strut and        the second shock strut cooperatively extend the levered landing        gear.    -   D1. A levered landing gear comprising:    -   a first shock strut having a first end and a second end;    -   a truck lever pivotally coupled to the second end of the first        shock strut; and    -   a second shock strut disposed between the second end of the        first shock strut and the truck lever, where the second shock        strut has a first end and a second end, the first end of the        second shock strut being coupled to the second end of the first        shock strut and the second end of the second shock strut being        coupled to the truck lever.    -   D2. The levered landing gear of paragraph D1, wherein the first        shock strut includes an outer cylinder forming the first end of        the first shock strut and an inner cylinder forming the second        end of the first shock strut and being at least partially        disposed within the outer cylinder, the outer cylinder being        configured for coupling with a vehicle frame and the inner        cylinder extends and retracts relative to the outer cylinder.    -   D3. The levered landing gear of paragraph D2, wherein the second        shock strut is disposed at least partially within the inner        cylinder.    -   D4. The levered landing gear of paragraph D2, wherein the second        shock strut includes a piston that reciprocates within the inner        cylinder.    -   D5. The levered landing gear of paragraph D4, further comprising        a connecting link coupling the piston to the truck lever.    -   D6. The levered landing gear of paragraph D2, wherein the second        shock strut includes an outer cylinder forming one of the first        end and second end of the second shock strut and an inner        cylinder forming the other of the first end and second end of        the second shock strut, where the second shock strut is        pivotally coupled to the inner cylinder of the first shock strut        and is directly pivotally coupled to the truck lever.    -   D7. The levered landing gear of paragraph D2, wherein the inner        cylinder includes an inner chamber, the inner chamber being        bifurcated into a first shock strut fluid compression chamber        and a second shock strut fluid compression chamber, where fluid        within the first shock strut compression chamber extends the        inner cylinder relative to the outer cylinder and fluid within        the second shock strut fluid compression chamber extends the        second shock strut relative to the inner cylinder.    -   D8. The levered landing gear of paragraph D7, wherein the second        shock strut comprises a strut cartridge inserted into the inner        chamber, where the strut cartridge bifurcates the inner chamber        and defines the second shock strut fluid compression chamber.    -   D9. The levered landing gear of paragraph D8, wherein the strut        cartridge comprises an elongated tube and an end cap, the end        cap defines a strut bulkhead of the first shock strut.    -   D10. The levered landing gear of paragraph D9, wherein the strut        bulkhead of the first shock strut includes a metering pin of the        first shock strut.    -   D11. The levered landing gear of paragraph D10, wherein the        metering pin of the first shock strut includes a first end        proximate the strut bulkhead, a distal end longitudinally        separated from the first end, and flutes longitudinally arranged        on the metering pin between the first end and the second end,        the flutes having a varying depth so that a fluid flow through        the flutes is greater at the second end than fluid flow through        the flutes at the first end.    -   D12. The levered landing gear of paragraph D2, further        comprising a stop member coupled to the inner cylinder, the stop        member including a stop surface configured to interface with the        truck lever such that reaction forces bypass the second shock        strut.    -   D13. The levered landing gear of paragraph D1, wherein    -   the truck lever includes a first end and a second end, the first        end being pivotally coupled to the first shock strut at a truck        lever pivot axis and the second end includes a wheel rotation        axis; and    -   a connecting link having a connecting link first end and a        connecting link second end opposite the connecting link first        end, the connecting link first end being coupled to the truck        lever between the truck lever pivot axis and the wheel rotation        axis, and the connecting link second end being coupled to the        second shock strut.    -   D14. The levered landing gear of paragraph D13, wherein the        connecting link is pivotally coupled to both the second shock        strut and the truck lever.    -   D15. The levered landing gear of paragraph D13, wherein the        truck lever includes but one wheel rotation axis.    -   D16. The levered landing gear of paragraph D1, wherein an        extension length of the levered landing gear is defined by a        combination of an extension length of the first shock strut and        an extension length of the second shock strut.    -   D17. The levered landing gear of paragraph D1, further        comprising at least one torsion link coupling an inner cylinder        and outer cylinder of the first shock strut.    -   D18. The levered landing gear of paragraph D17, wherein the at        least one torsion link is configured to prevent rotation of the        second shock strut relative to the first shock strut.    -   D19. The levered landing gear of paragraph D1, wherein the first        shock strut and the second shock strut are configured so as to        cooperate with each other to absorb landing energy.    -   D20. The levered landing gear of paragraph D1, wherein the first        shock strut and the second shock strut are configured so as to        cooperate with each other to extend the levered landing gear.    -   D21. The levered landing gear of paragraph D1, wherein the        second shock strut comprises:    -   a metering pin coupled to a mounting surface of a piston of the        second shock strut; and    -   an orifice plate that cooperates with the metering pin to meter        an amount of fluid flow as the second shock strut is compressed.    -   D22. The levered landing gear of paragraph D21, wherein the        metering pin includes a first end proximate the mounting surface        of the piston, a distal end longitudinally separated from the        first end, and flutes longitudinally arranged on the metering        pin between the first end and the second end, the flutes having        a varying depth so that a fluid flow through the flutes is        greater at the second end than fluid flow through the flutes at        the first end.    -   D23. The levered landing gear of paragraph D1, wherein the        second shock strut includes a strut cartridge and a piston that        reciprocates within the strut cartridge, the piston having a        first end including a connecting link mount and a second end,        longitudinally spaced from the first end.    -   D24. The levered landing gear of paragraph D23, wherein the        piston further comprises a first bearing disposed adjacent the        first end and a second bearing disposed adjacent the second end,        the first bearing and the second bearing being disposed between        the piston and the strut cartridge.    -   D25. The levered landing gear of paragraph D23, wherein the        piston further comprises a scraper that interfaces with the        strut cartridge, the scraper being configured to clean an        interior surface of the strut cartridge as the piston moves        within the strut cartridge.    -   D26. The levered landing gear of paragraph D1, wherein the first        shock strut includes variably sized oil passages configured to        control a load applied to a piston of the first shock strut.    -   D27. The levered landing gear of paragraph D1, wherein the        second shock strut includes variably sized oil passages        configured to control a load applied to a piston of the second        shock strut.    -   D28. The levered landing gear of paragraph D1, further        comprising a second shock strut service fitting disposed on the        first shock strut, and at least one fluid flow aperture        extending through a wall of a strut cartridge of the second        shock strut, wherein a space between an outer surface of the        second shock strut and an interior surface of the first shock        strut defines a fluid passage between the second shock strut        fitting and the at least one fluid flow aperture.    -   D29. An aircraft comprising the levered landing gear of any one        of paragraphs D1 to D28.    -   E1. A method of using a levered landing gear, the method        comprising:    -   extending a first shock strut and a second shock strut along a        common extension axis, wherein the second shock strut is        disposed concentrically with and/or within the first shock strut        along a longitudinal axis of the first shock strut; and    -   pivoting a truck lever relative to the first shock strut as the        first shock strut and the second shock strut extend along the        common extension axis, where the truck lever is coupled to both        the first shock strut and the second shock strut.    -   E2. The method of paragraph E1, wherein the first shock strut        and the second shock strut cooperatively absorb landing energy.    -   E3. The method of paragraph E1, wherein the first shock strut        and the second shock strut cooperatively extend the levered        landing gear.    -   E4. The method of paragraph E1, further comprising metering an        amount of fluid flow within the first shock strut as the first        shock strut is extended and compressed with at least a metering        pin of the first shock strut, where the metering pin includes        flutes each having a variable depth.    -   E5. The method of paragraph E1, further comprising metering an        amount of fluid flow within the second shock strut as the second        shock strut is extended and compressed with at least a metering        pin of the second shock strut, where the metering pin includes        flutes each having a variable depth.

In the figures, referred to above, solid lines, if any, connectingvarious elements and/or components may represent mechanical, electrical,fluid, optical, electromagnetic, wireless and other couplings and/orcombinations thereof. As used herein, “coupled” means associateddirectly as well as indirectly. For example, a member A may be directlyassociated with a member B, or may be indirectly associated therewith,e.g., via another member C. It will be understood that not allrelationships among the various disclosed elements are necessarilyrepresented. Accordingly, couplings other than those depicted in thedrawings may also exist. Dashed lines, if any, connecting blocksdesignating the various elements and/or components represent couplingssimilar in function and purpose to those represented by solid lines;however, couplings represented by the dashed lines may either beselectively provided or may relate to alternative examples of thepresent disclosure. Likewise, elements and/or components, if any,represented with dashed lines, indicate alternative examples of thepresent disclosure. One or more elements shown in solid and/or dashedlines may be omitted from a particular example without departing fromthe scope of the present disclosure. Environmental elements, if any, arerepresented with dotted lines. Virtual (imaginary) elements may also beshown for clarity. Those skilled in the art will appreciate that some ofthe features illustrated in the figures, may be combined in various wayswithout the need to include other features described in the figures,other drawing figures, and/or the accompanying disclosure, even thoughsuch combination or combinations are not explicitly illustrated herein.Similarly, additional features not limited to the examples presented,may be combined with some or all of the features shown and describedherein.

In FIG. 8 , referred to above, the blocks may represent operationsand/or portions thereof and lines connecting the various blocks do notimply any particular order or dependency of the operations or portionsthereof. Blocks represented by dashed lines indicate alternativeoperations and/or portions thereof. Dashed lines, if any, connecting thevarious blocks represent alternative dependencies of the operations orportions thereof. It will be understood that not all dependencies amongthe various disclosed operations are necessarily represented. FIG. 8 andthe accompanying disclosure describing the operations of the method(s)set forth herein should not be interpreted as necessarily determining asequence in which the operations are to be performed. Rather, althoughone illustrative order is indicated, it is to be understood that thesequence of the operations may be modified when appropriate.Accordingly, certain operations may be performed in a different order orsimultaneously. Additionally, those skilled in the art will appreciatethat not all operations described need be performed.

In the foregoing description, numerous specific details are set forth toprovide a thorough understanding of the disclosed concepts, which may bepracticed without some or all of these particulars. In other instances,details of known devices and/or processes have been omitted to avoidunnecessarily obscuring the disclosure. While some concepts will bedescribed in conjunction with specific examples, it will be understoodthat these examples are not intended to be limiting.

Unless otherwise indicated, the terms “first,” “second,” etc. are usedherein merely as labels, and are not intended to impose ordinal,positional, or hierarchical requirements on the items to which theseterms refer. Moreover, reference to, e.g., a “second” item does notrequire or preclude the existence of, e.g., a “first” or lower-numbereditem, and/or, e.g., a “third” or higher-numbered item.

Reference herein to “one example” means that one or more feature,structure, or characteristic described in connection with the example isincluded in at least one implementation. The phrase “one example” invarious places in the specification may or may not be referring to thesame example.

As used herein, a system, apparatus, structure, article, element,component, or hardware “configured to” perform a specified function isindeed capable of performing the specified function without anyalteration, rather than merely having potential to perform the specifiedfunction after further modification. In other words, the system,apparatus, structure, article, element, component, or hardware“configured to” perform a specified function is specifically selected,created, implemented, utilized, programmed, and/or designed for thepurpose of performing the specified function. As used herein,“configured to” denotes existing characteristics of a system, apparatus,structure, article, element, component, or hardware which enable thesystem, apparatus, structure, article, element, component, or hardwareto perform the specified function without further modification. Forpurposes of this disclosure, a system, apparatus, structure, article,element, component, or hardware described as being “configured to”perform a particular function may additionally or alternatively bedescribed as being “adapted to” and/or as being “operative to” performthat function.

Different examples of the apparatus(es) and method(s) disclosed hereininclude a variety of components, features, and functionalities. Itshould be understood that the various examples of the apparatus(es) andmethod(s) disclosed herein may include any of the components, features,and functionalities of any of the other examples of the apparatus(es)and method(s) disclosed herein in any combination, and all of suchpossibilities are intended to be within the scope of the presentdisclosure.

Many modifications of examples set forth herein will come to mind to oneskilled in the art to which the present disclosure pertains having thebenefit of the teachings presented in the foregoing descriptions and theassociated drawings.

Therefore, it is to be understood that the present disclosure is not tobe limited to the specific examples illustrated and that modificationsand other examples are intended to be included within the scope of theappended claims. Moreover, although the foregoing description and theassociated drawings describe examples of the present disclosure in thecontext of certain illustrative combinations of elements and/orfunctions, it should be appreciated that different combinations ofelements and/or functions may be provided by alternative implementationswithout departing from the scope of the appended claims. Accordingly,parenthetical reference numerals in the appended claims, if any, arepresented for illustrative purposes only and are not intended to limitthe scope of the claimed subject matter to the specific examplesprovided in the present disclosure.

What is claimed is:
 1. A levered landing gear comprising: a first shockstrut having a longitudinal axis; a second shock strut disposedconcentrically with the first shock strut along the longitudinal axissuch that the first shock strut and the second shock strut extend alonga common extension axis, the second shock strut comprises: a meteringpin coupled to a mounting surface of a piston of the second shock strut,and an orifice plate that cooperates with the metering pin to meter anamount of fluid flow as the second shock strut is compressed, whereinthe metering pin includes a first end proximate the mounting surface ofthe piston, a second end longitudinally separated from the first end,and flutes longitudinally arranged on the metering pin between the firstend and the second end, the flutes having a varying depth so that afluid flow through the flutes is greater at the second end than fluidflow through the flutes at the first end; and a truck lever coupled toboth the first shock strut and the second shock strut such that thesecond shock strut pivots the truck lever relative to the first shockstrut.
 2. The levered landing gear of claim 1, wherein the truck leverincludes a first end and a second end, the first end being pivotallycoupled to the first shock strut at a truck lever pivot axis and thesecond end includes a wheel rotation axis; and a connecting link havinga connecting link first end and a connecting link second end oppositethe connecting link first end, the connecting link first end beingcoupled to the truck lever between the truck lever pivot axis and thewheel rotation axis, and the connecting link second end being coupled tothe second shock strut.
 3. The levered landing gear of claim 2, whereinthe truck lever includes one wheel rotation axis.
 4. The levered landinggear of claim 1, further comprising at least one torsion link assemblycoupling an inner cylinder and outer cylinder of the first shock strut.5. The levered landing gear of claim 4, wherein the at least one torsionlink assembly is configured to prevent rotation of the second shockstrut relative to the first shock strut.
 6. The levered landing gear ofclaim 1, wherein the first shock strut includes an outer cylinder and aninner cylinder at least partially disposed within the outer cylinder,the outer cylinder being configured for coupling with a vehicle frameand the inner cylinder extends and retracts relative to the outercylinder.
 7. The levered landing gear of claim 6, wherein the secondshock strut is disposed at least partially within the inner cylinder. 8.The levered landing gear of claim 6, further comprising a stop membercoupled to the inner cylinder, the stop member including a stop surfaceconfigured to interface with the truck lever such that reaction forcesbypass the second shock strut.
 9. The levered landing gear of claim 6,wherein the second shock strut includes a piston that reciprocateswithin the inner cylinder.
 10. The levered landing gear of claim 9,further comprising a connecting link coupling the piston to the trucklever.
 11. The levered landing gear of claim 6, wherein the innercylinder includes an inner chamber, the inner chamber being bifurcatedinto a first shock strut fluid compression chamber and a second shockstrut fluid compression chamber, where fluid within the first shockstrut compression chamber extends the inner cylinder relative to theouter cylinder and fluid within the second shock strut fluid compressionchamber extends the second shock strut relative to the inner cylinder.12. The levered landing gear of claim 11, wherein the second shock strutcomprises a strut cartridge inserted into the inner chamber, where thestrut cartridge bifurcates the inner chamber and defines the secondshock strut fluid compression chamber.
 13. The levered landing gear ofclaim 12, wherein the strut cartridge comprises an elongated tube and anend cap, the end cap defines a strut bulkhead of the first shock strut.14. The levered landing gear of claim 13, wherein the strut bulkhead ofthe first shock strut includes a metering pin of the first shock strut.15. A method of using a levered landing gear, the method comprising:extending a first shock strut and a second shock strut along a commonextension axis, wherein the second shock strut is disposedconcentrically with and/or within the first shock strut along alongitudinal axis of the first shock strut; pivoting a truck leverrelative to the first shock strut as the first shock strut and thesecond shock strut extend along the common extension axis, where thetruck lever is coupled to both the first shock strut and the secondshock strut; and metering an amount of fluid flow within the first shockstrut as the first shock strut is extended and compressed with at leasta metering pin of the first shock strut, where the metering pin includesflutes each having a variable depth.
 16. The method of paragraph 15,wherein the first shock strut and the second shock strut cooperativelyabsorb landing energy.
 17. The method of paragraph 15, wherein the firstshock strut and the second shock strut cooperatively extend the leveredlanding gear.
 18. A method of using a levered landing gear, the methodcomprising: extending a first shock strut and a second shock strut alonga common extension axis, wherein the second shock strut is disposedconcentrically with and/or within the first shock strut along alongitudinal axis of the first shock strut; pivoting a truck leverrelative to the first shock strut as the first shock strut and thesecond shock strut extend along the common extension axis, where thetruck lever is coupled to both the first shock strut and the secondshock strut; and metering an amount of fluid flow within the secondshock strut as the second shock strut is extended and compressed with atleast a metering pin of the second shock strut, where the metering pinincludes flutes each having a variable depth.
 19. The method ofparagraph 18, wherein the first shock strut and the second shock strutcooperatively absorb landing energy.
 20. The method of paragraph 18,wherein the first shock strut and the second shock strut cooperativelyextend the levered landing gear.